How do you find the slope for $ y-3=0 $ ?

Hint: To find the slope of the given equation. First of all, we are going to write this equation in the form of $ y=mx+c $. This equation is the general form of the equation of a straight line. In this equation, m is the slope of the line. So, after writing the given equation in this general equation form, we are going to compare both these equations and find the value of m (which is the slope).

Complete step by step answer:
The equation given in the above problem of which we have to find the slope is as follows:
 $ y-3=0 $ ……… Eq. (1)
We know that the above equation is the equation of a straight line. The general form of the equation of a straight line is as follows:
 $ y=mx+c $
Now, we are writing the given equation in the form of the above equation so that we will get the value of slope which is “m” in the above equation.
Rearranging eq. (1) by adding 3 on both the sides we get,
 $ \begin{align}
  & y-3+3=3 \\
 & \Rightarrow y=3 \\
\end{align} $
In the above equation, coefficient of x is 0 so writing x and multiplying 0 with it we get,
 $ y=0.x+3 $
Now, comparing the above equation with $ y=mx+c $ we get the value of “m” as 0 which you can see from the below:
 $ y=0.x+3 $
 $ y=mx+c $
Hence, we got the slope of this given equation as 0.

Note:
 In the above question, we are asked to find the slope of the above equation. In some questions, you might ask to find the y-intercept of the given equation. This y-intercept calculation is done by finding the value of c in the general form of the equation of the straight line which we have shown above as follows:
 $ y=mx+c $ ……. Eq. (2)
Now, we have written the given equation of a straight line in the above form of equation i.e.:
 $ y=0.x+3 $ ………. Eq. (3)
On comparing eq. (2) with eq. (3) we get the value of c as 3. Hence, the y-intercept of the given equation is 3.